Endless coated abrasive articles, such as belts, sleeves and tubes are used in a variety of abrading operations, especially in the woodworking and metal finishing industries. These operations typically require that the articles be made and supplied by the coated abrasive manufacturer in a large variety of widths and circumferences.
Techniques for making endless coated abrasive belts are known in the art and include those utilizing lap joints and butt splices. Lap joints can be provided, for example, by cutting a coated abrasive material into an elongate strip of a desired width and length. The two free ends of the elongate strip are respectively beveled to have a top end and a bottom end which can be superposed to form a joint. The beveled ends are then overlapped and joined adhesively or mechanically. Butt splices can be provided, for example, by mating the two free ends of the elongate strip into a juxtaposed relationship at a juncture line. The bottom surface of the backing at each end of the elongate strip is then coated with an adhesive, mechanically secured, or otherwise attached, and may be overlaid with a strong, thin, tear-resistant, splicing media in the joint area. The endless coated abrasive belt may, for example, be subsequently slit into narrower widths.
Coated abrasive belts in widths greater than the width of the coated abrasive material have been produced by a number of methods. One such method involves piecing together segments of coated abrasive material to form wide, multi-jointed sectional belts that cover a broad range of belt widths and belt circumferences. These belts, however, have the drawback of increased cost due to the multiple piecing and joining processes required to fabricate the belts. In addition, multiple joints increase the potential for problems due to weakening of the belt at the joints, as well as process control and quality issues.
Another method of forming an endless coated abrasive belt that has a width greater than the width of coated abrasive material from which it was made involves spiral winding of material. A conventional method for making such xe2x80x9cspiral woundxe2x80x9d belts involves winding an inner liner spirally on a mandrel having an outer circumference equal to the inside circumference of the desired abrasive belt, applying an adhesive to the outer major surface of the inner liner, and winding spirally over the adhesive layer a strip of coated abrasive material. Such a method is widely used for the fabrication of belts in smaller sizes, up to, for example, 6 inches (15.2 cm) in diameter or 19 inches (48.3 cm) in circumference.
Another such method involves spiral winding narrow strips of coated abrasive material having scarfed (or angle cut) edges that overlap and are adhered using conventional techniques. Also, the edges of a piece of wider coated abrasive material may be formed to abut when wound spirally within a revolvable drum. Subsequently, a resinous coating material is applied to the inner periphery of the belt which then spreads, as the drum revolves, to form a continuous layer of resinous coating that joins the belt material together. Yet another method involves spiral winding about a mandrel a coated abrasive material with abutting edges that has a flexible backing material including a layer of hot-melt adhesive. The spiral wound material is then heated to cause the hot-melt adhesive to flow across the abutted edges, resulting in a continuous layer that secures the edges together.
An ongoing need exists for spiral wound abrasive belts that are produced in a faster, cheaper and more efficient manner, and in a variety of sizes. Such spiral wound belts that take advantage of abrasive media constructions that produce stronger and more durable abrasive articles are also desirable.
Aspects of the present invention include an apparatus and method for forming an endless spiral wound abrasive article and the resulting article. The apparatus includes first and second spaced-apart hubs, configured so that a portion of first and second webs passing between the first hub and the second hub is oriented substantially in a plane which remains stationery even if a position of one of the hubs is changed. The apparatus further includes winders and a web joiner. The method includes providing a second web which includes an adhesive disposed on a first major surface and a liner releasably affixed to the adhesive. The method includes removing the liner from the second web before positioning the second web adjacent the first web. The first and second webs are wound about the first and second hubs to form a spiral wound article having a desired circumference.